1. Field of the Invention
The present invention relates to a wireless locking/unlocking device which is applicable to an opening/closing body such as automobile door and locks/unlocks that opening/closing body through communication with a portable unit. More particularly, the present invention relates to a wireless locking/unlocking device which achieves radio communication between a portable unit to which an inherent code is allocated and an on-vehicle unit and if no response occurs to a request signal transmitted from the on-vehicle unit, automatically locks the opening/closing body in order to prevent wasteful responses of the portable unit, in other words, prevent unnecessary communication between the on-vehicle unit and the portable unit thereby blocking waste loss of electricity.
2. Description of the Related Art
Japanese Patent Application Laid-Open No.SH062-37479 (conventional art 1) and Japanese Patent Application Laid-Open No.HEI10-238184 (conventional art 2) have disclosed automatic locking systems which comprise an on-vehicle unit and a portable unit which receives a request signal transmitted from the on-vehicle unit and sends back a response signal and if a driver or a passenger carrying the portable unit leaves the vehicle, the opening/closing body such as door or trunk is automatically locked.
According to the conventional art 1, if all doors are closed, a request signal is transmitted from a transmitter of the on-vehicle unit provided on a door mirror on driver' seat side or driver's seat to surrounding of the vehicle including its vehicle compartment (step S600 in FIG. 7). If no response signal is sent back from the portable unit in response to this request signal, it is determined that the portable unit is not being used and then an auto lock mode is released (negative in determination in step S601).
If the response signal is sent back, the request signal is sent intermittently (steps S603, S604, S605), when the response signal from the portable unit is interrupted, respective doors are locked (steps S606, S607). According to the conventional art 2, if the response signal from the portable unit is interrupted, the respective doors are locked.
According to the above-described conventional technology, even if auto lock is unnecessary like in a case where a vehicle driver opens and closes its door to ride on the vehicle, the request signal is transmitted to surrounding of the vehicle. Because this request signal passes through the vehicle windows and penetrates into the vehicle compartment because of the characteristic of radio propagation, existence of the portable unit is detected by the request signal sent when all the doors are closed, although the vehicle driver is riding on the vehicle and therefore, the request signal continues to be sent intermittently after that. Thus, the portable unit is driven to send wasteful responsive signals, so that electric power is consumed wastefully.
According to the conventional technology 1, even if auto lock is unnecessary like in a case where a vehicle driver opens the door [FIG. 13(a)] and rides on it [FIG. 13(b)], the request signal RQ is sent [FIG. 13(c)] if all the doors are closed. Then, the portable unit 2 responds to this and therefore, intermittent transmission of the request signal is continued [FIG. 13(d)], so that the portable unit 2 is driven to send wasteful response signals.
According to the conventional technology 1, if no response signal is returned to a request signal sent just after all the doors are closed, it is determined that the portable unit is not being used, so that auto lock is not executed. Thus, if, as shown in FIG. 14, a vehicle driver carrying the portable unit 2 and a passenger carrying no portable unit open its door so as to get out of the vehicle [FIG. 14(a), (b)], the vehicle driver closes the driver's seat side door [FIG. 14(c)] and leaves the vehicle body and after that, the passenger seat side door is closed so that all the doors are closed [FIG. 14(d)], the request signal RQ is sent to the vicinity of the driver's seat side door including the vehicle compartment.
However, because the portable unit 2 of the vehicle driver is located out of the effective transmission zone of the request signal, it is determined that the portable unit 2 is not being used and then, auto lock is not executed [FIG. 14(e)]. The effective transmission zone of the request signal refers to an effective arrival range which allows the request signal sent from the on-vehicle unit to be received by the portable unit.
In the Japanese Patent Application Laid-Open No.2001-140517 (conventional technology 3), such a technological problem that if user of the portable unit closes the door violently while leaving the vehicle body, the portable unit cannot respond to a request signal because the vehicle driver (portable unit) has already left out of the effective transmission zone, so that the auto lock function is not valid has been recognized and then, a technology for solving this problem has been proposed.
According to the conventional technology 3, the position of the portable unit is detected not only when the door is opened but also when it is closed, and the possible states are classified into four combinations (patterns 1 to 4) of which the portable unit exists within the vehicle compartment or outside the vehicle compartment when the door is closed, a case (pattern 4) where the portable unit does not exist within the vehicle compartment or outside the vehicle compartment when the door is closed, and combinations (patterns 4, 5) of whether or not the portable unit exists outside the vehicle compartment when the door is opened and different control styles are adopted for each classified state.
In this case, even if no portable unit exists within the vehicle compartment or outside the vehicle compartment when the door is closed, if it is recognized that the portable unit existed within the vehicle compartment at the time of door opening just before, automatic locking is carried out (pattern 4). Thus, even if the vehicle driver closes the door violently while leaving the vehicle or a passenger closes the door later, the automatic locking is also carried out.
Because the conventional technology 3 does not distinguish the “riding on the vehicle” from “getting out of the vehicle”, the “door closing key detection” shown in FIG. 7 is always carried out when the door is closed. Thus, if the portable unit exists in a zone A within the vehicle compartment also like when a carrier of the portable unit closes the door after he rides on the vehicle, the request signal is always sent three times (S32→S33→S36→S37→S32 . . . ). For that reason, the technical problem that the vehicle battery and the portable unit battery are consumed wastefully has not been solved yet.
According to the conventional technology 3, when the door is opened or closed, “door opening key detection (FIG. 6)”, “door closing key detection (FIG. 7)” and “door lock standby program (FIG. 8)” for detecting that a vehicle driver leaves the vehicle are executed and during each processing, communication is always established to detect the position of the portable unit. For that reason, because communication is always established through the above-described three processings each time when a person not carrying the portable unit opens or closed the driver's seat side door in order to ride on or get out of the vehicle for cleaning the vehicle compartment, power of the vehicle battery is consumed wastefully. Further, if the portable unit cannot be detected at any time of door opening/closing (pattern 5 in FIG. 9), an alarm is automatically raised after a predetermined time elapses, so that automatic locking is executed, which is a new problem to be solved.
The effective transmission zone in which the sent request signal can be received by the portable unit securely is affected by disturbance noise, so that it is reduced or expanded with respect to a preliminarily set effective transmission zone. For that reason, it is difficult to recognize the position of the portable unit accurately.